Activating conductor of the second



April 1946- R. E. STARK 2,398,866

ACTIVATING CONDUCTORS OF THE SECOND CLASS Fled March 19, 1942 fi llllllllll 6 BY WWW/flaw j ATTORNEYS Figure 1;

Patented Apr. 23, 1946 ACTIVATING CONDUCTOR OF THE SEQOND CLASS Rawson E. Stark, Greensburg, Pa., assignor to Stupakofl Ceramic & Manufacturing 00., a corporation of Pennsylvania Application March 19, 1942, Serial No. 435,399

' 18 Claims.

This invention pertains to electric circuits employing conductors of the second class, i. e. materials which are insulators when cold but which are electrically conductive when hot. The present invention relates more particularly to the heating or activation, of such conductors. These glowers, some of which are available under the trade name of Insulcon are. used as generators for infra red rays, for signallingpurposes; as igniters in oil burning equipment; and as heaters as well as for illuminating purposes. Heretofore the means for heating these conductors has usual.- ly comprised a resistance heater arranged to radiate heat to the glower or conductor of the second class, the resistance in turn requiring various complicated control circuit arrangements forcutting out the resistance after the glower has become conductive. The present invention provides a simple means for heating such glowers or conductors which very substantially simplifies .the equipment required and which is inherently automatic. The present invention is based on the use of a high voltage electric are which is' self-extinguishing as used in associated circuits. .The electric arc heats the element and then in turn extinguishes itself. If the element fails to operate on the first heating the arc will reestablish itself and repeat the operation until the glower or elementbecomes conductive.

For the-purposes of the present invention the conductor of the second class will hereinafter be referred to as a glower.

The invention may be more fully understood by reference to the accompanying drawing, in which:

Figure 1 is a diagram of a glower and a high voltage are circuit for activating the glower;

Figure 2 is a schematic illustration of atransformer such as may Figure 3 is a diagram of a modified circuit;

Figure 4 is a similar view of a still further modification; and j c Figure 5 shows the operation of a number of glowers from a common transformer structure.

Referring first to Figure 1, the glower is desigbe used in connection with I where the electrodes are so far apart that the by a much wider gap. These electrodes are in a circuit 8 including a'secondary winding 9 which.

is also a part of the transformer 456. The winding 9 is a high voltage winding so that the current inducedin the circuit 8 is a relatively high voltage current, being of the order of that used commercially in neon tubes, 1. e. somewhere in the neighborhood of 3,000 volts.

In the operation of the device shown in Figure 1 the primary winding 6 is connected to a source .of alternating or pulsating direct current. Voltage is initially induced in the circuit 8 which includes the electrodes 1. An arc is caused to form between the two electrodes of the gap 1 at the point 'where the electrodes are closest together. As the arc continues to operate it will gradually climb up the electrodes until it reaches a level arc extinguishes itself. The heat from the arc activates the glower 2 rendering it conductive, whereupon a current then flows through the circuit 3 to energize the glower. The transformer for the glower! may be a-constant current transformer so as to limit the amount of current which may be supplied to the glower 2. Any well known constant current transformer may be employed for the purpose, although one specially designed for the purpose is preferable. The transformer may also be so designed that after the glower 2 begins to operate the arc circuit will be starved" and the arc will. therefore cease to operate after glower 2 has become conductive. If however, the

glower 2 on the first or succeeding operation does not become sufllciently hot the arc will reestabnated 2. It is included in a circuit 3 which is in series with the secondary winding 4 or a transformer. The transformer has a, core 5 and a primary 6. Located under the glower are two spaced electrodes, designated 1, .of a relatively refractory or conductive material. The two electrodes may be parallel but preferably are sloped upwardly away from each other so that while the lower terminals are relatively close together the upper portions of the electrodes are separated lish'itself and the cycle will be repeated and this will continue until the glower has become con- .ductive.

The transformer which operates the glower is preferably a constant current transformer, as, by the use of such a transformer the current supplied the glower is limited to the maximum current output of the transformer, and the usual ballasting or stabilizing circuits are not required. A- transformer of the so-called neon type, i. e. one developed for the operation of neon tubes, is

highly suitable because of its constant current characteristic. A number of glowers may be operated from the same transformer structure, each from a separate secondary and the operation or shutting down of one will not afl'ect the other.

Figure 2. indicates diagrammatically one form of constant current transformer which I have developed for this purpose. The core of the trans- I former is in the form of a closed rectangle and the windings 8, 4 and 9 are arranged alongone side of the core. Between the windings l and I is a bridge or leakage core H. When the wind-' ing 6 is initially energized the magnetic flux will be around the rectangular core II and a potential will be induced immediately in the winding 2 to establish the are. When the glower 2 has become conductive and the secondary winding 4 begins to draw current the lines of flux will partially pass across iron shunt ii, thereby reducing potential both in coils 9 and 4,,whereupon current in coil 4 will assume constant current equilibrium and the reduced flux through the ring circuit, and the coil 9 will have an insumcient potential to again start an are so long as the glower is conductive. It is well understood in the art that by varying the quantity of material in the shunt II or varying the gap Ila the output of the coil 4 may be properly established.

In the modification shown in Figure 3 the glower is designated l2. It is included in a circuit I3 which circuit includes in addition to a source of current (not shown) the secondary ll of a radio frequency or high frequency transformer. The two inclined electrodes are designated II and they are connected in parallel with the glower l2. A by-pass condenser is indicated in the circuit at It. The primary of the radio or high frequency transformer is designated i1 and is included in any suitable circuit l8 having a high frequency generator as for example a vacuum tube oscillator. In operation when the primary winding i1 is energized high voltage current is induced in the secondary M. This initiates the operation of the arc across the electrodes at It. The are may thereafter operate from a current in the circuit i3 or it may continue to be fed from the high frequency source. As previously described the arc will continue to operate until it extinguishes itself and in 30 operating it will heat the glower (2. As soon as the glower I2 becomes conductive the arm I is short circuited and the arc will thereafter be unable to reestablish itself.

Figure 4 illustrates a modification in which a source of direct current is used for operating the glower. In this view 20 designates the glower, 2| i a fixed or ballasting resistor, 22 is a relay and 23 a source of direct current. The relay controls a circuit 24 connected in parallel with the glower 20, this circuit 24 including an induction coil 25 with an interrupter at 26. Connected across the secondary 21 of the induction coil are electrodes 28 similar to those previously described for establishing an arc, these electrodes being upwardly divergent as previously described and being so disposed that the heat generated by the arc will activate the glower 20. In the arrangement shown in Figure 4, the closing of the circuit including the source of power 23 will initially actuate the induction coil 2!, the relay circuit 22 at this time being closed. Operation of the induction coil will establish an arc across the elec-' trodes 28. When the glower 20 has become conductive the relay 22 will operate to open the clra.

cult through the induction coil.

In Figure 5 I have shown a constant current transformer operating a number of Blowers, and

the operation of one will not influence the others.

In this figure, 30 is the core of the transformer,

II the primary winding and I2 are ,secondary windings, each connected to its own glower 23. The shunts in the transformer core are designated 24.

While I have illustrated and described certain specific embodiments of my invention it will be understood that this is merely by way of illustration and that various modifications and changes may be made in the arc circuit within the contemplation of my invention and under the scope of the following claims. The invention constitutes a substantial improvement over previous activating circuits through the use of an are which extinguishes itself after a predetermined period of operation and which will not again operate so long as the giower is conductive. The use of this are substantially simplifies the equipment which is required for a glower installation and since the electrodes for establishing the are are disintegrated much less rapidly than a resistor in close relation to the glower the present invention provides an arrangement which has a much longer life than equipment heretofore commonly used. Moreover, through, the use of constant current transformers, the glowers are automatically prevented from overheating or drawing an increasingly heavier current as their temperature increases. Starting of the glowers on the other hand is facilitated because a maximum potential is available across the terminals of the glower from the beginning, and the higher the potential, the lower the temperature at which conduction begins.

I claim as my invention:

1. For use in heating a conductor of the sec- 0nd class, fixed spaced upwardly extending electrodes adjacent the conductor arranged to generate an are for heating the same, a high voltage circuit including the electrodes for generating the arc, and means for starving the arc to render the said are self-extinguishing responsively to the conductor reaching operating temperature.

2. For use in heating a conductor of the second class, fixed spaced upwardly extending and upwardly divergent electrodes adjacent the conductor arranged to generate an are for heatin the conductor, means for impressing sufilcient energizing said last-named means when the con-' ductor reaches a conducting temperature, the said means automatically starving the arc to render the same self-extinguishing responsively to the conductor reaching operating temperature.

4. For use in heating a conductor of the second class, relatively fixed spaced upwardly ex tending and upwardly diverging electrodes ad- -Jacent the conductor for generating an arc to heat the same, and a common circuit for the conductor and the electrodes so disposed that operation of the conductor deprives the electrodes of sufficient current to function, the circuit including means for generating a voltage sufllciently high to spontaneously initiate an arc across the electrodes.

5. Apparatus of the class described comprising a conductor of the second c1ass,.relatively fixed upwardly extending and upwardly diverging electrodes adjacent the conductor for gencrating an arc to heat the same, a source ofcurrent for operating the arc and for operating the conductor, a. circuit for the electrodes and a circuit for the conductor the circuits being so connected that operation of the conductor starves the electrodes of operating current and renders the arc self-extinguishing responsively to the conductor reaching operating temperature, the circuit for the electrodes including means for generating a voltage sufliciently high to initiate the arc.

6. Apparatus of the class described comprising tively fixed spaced upwardly diverging electrodes adjacent the conductor for generating an arc to heat the same, and a common electrical circuit a conductor of the second class, a pair of rela- I for the conductor and the electrodes, said circuit including one transformer" winding for energizing the conductor and another transformer winding for energizing the arc, said circuits being so arranged that operation of the conductor deprives the electrodes of an operating potential.

7. Apparatus of the class described comprising a plurality of glower units each being a conductor of the second class, a source of current, and a transformer having a primary connected to the source of current andhaving a plurality of secondary windings and a core with shunts therein soarranged that each secondary has a substantially constant current characteristic, one of said glower units being connected across each of said secondary windings whereby all or any number of said glower units may be operated simultaneously.

8. An electrical circuit comprising a constant current variable potential source, a. conductor element of the-second class connected to said source and means for creating ahigh potential discharge adjacent said conductor for heating the same, said means comprising fixed spaced electrodes, a source of high potential current connected with the electrodes, and means for diminishing the flow. of high potential current to the electrodes responsively to increase ofcurrent flow through the conductor as the said conductor reaches a desired temperature, thereby automatically'terminating the flow of current to the said electrodes while the conductor is at the said v desired temperature. i

9. A control system for controlling activation of a conductor of the second class, which com-. prises the combination with a source of current, of a transformer having its primary winding in circuit with a source of current, a circuit for the said conductor of the second class, the said circult including a high voltage secondary winding of the transformer and electrode means adjacent to the said conductor of the second class, the said high voltage secondary winding of the trans former being adapted to establish an arc between the electrode means, and means for starving the arc responsively to activation of the said conductor of the second class by the said arc, thereby extinguishing the arc responsively to the said activation of the conductor of the second class.

10. A control system for controlling activation of a conductor of the second class, which com'--.

prises the combination with a source of current, of a constant current transformer having its primary coil in circuit with the source of current, a circuit for the said conductor of the second class, the said circuit including' a secondary coil of the constant current transformer, a second circuit for activating the said conductor of the second class. the second circuit including a high voltage secondary windingfor. theponstant current transficient potential across the electrode means to generate an arc, the said electrode means being inclined towards each other in a direction away from the said conductor of the second class, the said are being adapted to heat the conductor of the second class to actuate the same, and 'means for starving the arc responsively to activation of the said conductor of the second class by the arc, thereby extinguishing the arc responsively to the actlvationof the conductor of the second class.

12. A control system for controlling activation of a. conductor of the second class, which comprises, in combination, a transformer having its primary winding in circuit with a source of current, a circuit for the said conductor of the second class, the said circuit including a high voltage secondary Winding of the transformer, electrode means adjacent to the said conductor, the said high voltage secondary winding of the transrormer being adapted to establish an are between the electrode means, the said electrode means including electrodes inclined towards each other so that they diverge away from each other towards the said conductor andmeans for starving the arc responsively to activation of-the said conductor by the arc, thereby extinguishing the arc responsively to the activation of the conductor, the said means for starving the arccausing the arc to travel through progressively longer distances between the diverging electrode means as. it approaches the said conductor until the distance between the electrode means becomes too great to be bridged by the arc, which thereby becomes automatically extinguished as the said conductor is activated by heat generated by the arc priorto extinguishing thereof.

13. A control system for controlling activation 01' a conductor of the second class, which comprises the combination with the said conductor and a circuit therefor, of fixed spaced upwardly extending electrodes adjacent to the-conductor, a.

hish voltage circuit including the electrodes adapted to generate an arc between the said electrodes for heating the conductor to acutatin temperature, and means for diminishing current supplied to the electrodes responsively to increase former, and electrode means adjacent to the said conductor of the second class, the high voltage secondary winding being adapted to establish an of current flow through the conductor.

14. Acontrol system for controlling activation of a conductor oi! the second class, which comprises the combination with the saidconductor and a circuit therefor, of fixed spaced electrodes,

9. high voltage circuit including the electrodes.

adapted to generate an are between the said electrodes for activating the 'said conductor, and

means for starving the arc responsively to the said conductor reaching actuation temperature to automatically extinguish the arc.

15. A control system for controlling activation of a conductor of the'second class, which comprises the combination with the'said conductor, and a circuit therefor, of fixed spaced upwardly extending electrodes adjacent to the conductor, .a

common circuit for the conductor and electrodes,

means in the circuit for generating a voltage uiflciently high to spontaneously initiate and maintain an arc across the electrodes, and means for the said common circuit operable responsively to activation of the said conductor by the arc to automatically deprive the electrodes of sufiicient current to maintain the said arc.

16. In apparatus oi the class described, including a glower unit, which is a conductor of the second class, and instrumentalities for activating the said glower, the invention which consists in a constant current transformer having a secondary across which the glower is connected, another secondary across which the control instrumentalities are connected, and a shunt adapted to reduce potentiai in both secondaries, whereby the second ary for the slower assumes constant current equilibrium and the secondary for the control instrumentalities reaches a potential insuflicient to actuate the control instrumentalities responsiveiy to the secondaryior the slower assuming the said constant current equilibrium.

1'1. 1n apparatus 01 the class described, inciudin: a slower unit, which is a conductor oi the second class, and instrumentalities for activating the said slower, the invention which consists in a constant current transformer having a closed annular core, a primary winding, and two secondary windinzs. around the core. the slower being connected across one or the secondary windings and the actuating instrumentalitiea for the slower being connected across the second secondary winding, and a leakaze core extending across the transformer to bridge the said annular core, the said leakage core being intermediate the primary winding and its adjacent secondary winding. and adapted to reduce potentials in both secondary windings until current in the secondary-winding for the slower assumes constant current equilibrium and the secondary winding for the sloweractivating instrumentalities is starved of current until it has an insumcient potential to activate the said instrumentalities as long as the slower is conductive.

18. In apparatus 01' the class described including agpiurality of flower units each oi which is a conductor of the second class, and instrumentalities for activatinfl the glowers, the invention which consists of a primary adapted to be connccted to a source oi current, a plurality of secondary windings, a core, and shunt means disposed across the core to bridie the core. the said shunt means being adapted to impart constant current characteristics to each of the sec ndary windings, one of the said slower units beinl connected across each of the secondary windinu, whereby any selected number of the giower units may be operated simultaneously.

RAWBON E. STARK. 

